Heretofore, in order to suppress radiation for heat rays thereby to reduce the burden of cooling and heating, a laminate having a low emissivity has been used for window glass of buildings, automobiles, etc. A laminate comprises, for example, a transparent substrate such as a glass substrate and a heat ray-shielding film formed on the substrate. Such a laminate is required to have a low heat emissivity so as to keep the heat in a room, a heat ray-shielding film is usually required to have a low emissive metal layer, and for example, one having a dielectric layer, a metal layer and a dielectric layer formed in this order, and one further having a metal layer and a dielectric layer repeatedly formed in addition, have been known. Such a heat ray-shielding film is also called a Low-E (low-emissivity) film, and glass having such a film formed thereon is called Low-E glass.
As a dielectric layer, one containing tin oxide, zinc oxide or antimony oxide as the main component has been known. Further, as the metal layer, one containing silver, gold, copper, palladium or rhodium as the main component has been known. As a representative laminate, for example, one which comprises a dielectric layer containing zinc oxide as the main component and a metal layer containing silver or a silver alloy as the main component has been known (for example, Patent Document 1 or 2).
A laminate is usually used as double glass or laminated glass, and during storage of a laminate after film formation until a step of assembling double glass or until a step for producing laminated glass, white spots will form by moisture in the environment, and the laminate is not necessarily excellent in storage property or handling efficiency. A reduction of the internal stress of the dielectric layer as the uppermost layer has been known to be effective for improvement of the moisture resistance, and as such a layer, a tin oxide film or a zinc oxide film which has another element having an ionic radius smaller than a bivalent zinc ion in an oxidized state added thereto has been known.
However, in a case where a laminate having the above tin oxide film, zinc oxide film or the like is produced by a large deposition apparatus to be used for production of glass for buildings or glass for automobiles, the internal stress may not sufficiently be lowered by moisture remaining in the sputtering apparatus, and the moisture resistance of the resulting laminate is insufficient in some cases. In order to further improve the moisture resistance, it has been known to form at least one dielectric layer, for example, by sputtering using a target containing zinc, tin or the like as the main component in an atmosphere containing a gas containing carbon atoms (for example, Patent Document 3).